1. Field of the Invention
The present invention relates to a light source device and an image pick-up apparatus provided with the same. In particular, the invention relates to a short-range light source device for use with an image pick-up apparatus and the image pick-up apparatus provided with the same.
2. Description of Related Art
The advancement in modern optical technologies obfuscates differentiations among various image pick-up devices, such as, for example, video recorders, cameras, camera phones and so forth, and progressively enables more and more consistent functions among them. As a result, the effective image capture range is gradually expanded, and objects in front of the lens within a close proximity of simply several centimeters can be clearly recorded even with a general camera phone. As the photographic distance becomes smaller, the image of the target object may occupy the entire screen. However, light beams diffused from the target object are not augmented. In other words, the picture inevitably gets dimmer when the photographic distance is gradually shortened, or even in the end becomes unable to be distinctly analyzed.
Short-range image capture is an important technology, especially with regards to many professional fields like dermatological treatment or criminal identification, including diagnoses of dermatoses, pre- and post-operation effects tracking on medical cosmetic surgeries, and verification of specific fluorescent reaction substances for example, in a body fluid, all of which require precisely recorded image data. However, compared with photographic demands in terms of common daily lives, voyages etc., the aforementioned requirements attract less people's attention, and, for commercial reasons, general camera manufacturers are not quite interested in making serious responses to this type of light supplement needs.
A conventional light supplement device is shown in FIG. 1, wherein two flashlights 81 are directly mounted, one in left and one in right, on the front side of a close-range photographic lens 90 of a camera 9. In taking a picture, the shutter button 91 sends a signal to trigger the two flashlights 81, so as to generate synchronous flash illumination, thereby providing the camera with light supplement. Unfortunately, such a type of light supplement can only offer transient illumination and fails to provide continuous illumination. Consequently, it cannot be used in the technical fields that require illumination of relatively longer duration, such as criminal identification for fluorescent reaction generated by means of continuous illuminations on different areas to achieve protein spotting, and dermatological treatment in which continuous illumination is used to effectively locate niduses of skin cancer. Moreover, the conventional device, once discharged, needs a little while to be recharged to perform next lighting, thus restricting user's operation. In particular, transient light emissions of overly high intensity from a general flashlight, after short-range flashes thereof, may cause brief visual saturation and temporary blindness in user's eyes, which is unfavorable for user's operation as well. Besides, the angle of the flashlights may undesirably lead to significant shadows or light reflections hard to be eliminated.
Another conventional light supplement device is shown in FIG. 2, wherein a light emitting diode 820 is installed at the front end of a bellow tube 82, and a power line passes through the bellow tube 82 to acquire electric energy from the camera 9, thereby allowing a photographer to manually adjust the bellow tube 82 to an appropriate angle in order to provide light supplement for the desired photographic position. In this way, seeing that the adopted light source is the light emitting diode 820, it is possible to provide light supplement of longer duration in time, thereby somewhat improving the aforementioned problem of transient flash. However, the effect of light supplement may be lower than expected because the angle of the bellow tube 82 cannot be precisely adjusted. Further, the structure of the bellow tube 82 may become problematic in reception, unfavorable for outdoor portability. Especially, since the bellow tube 82 need to be bent towards the lens 90 during use, in the case where a target object located in front of the lens 90 at a distance as short as 3 centimeters, for example, the bellow tube 82 would be very difficult to be bent over within such a narrow 3-centimeter interval; even barely pulled in, the angle of provided light supplement would usually become vertical to the light axis direction of the lens 90. Accordingly, light cannot be effectively projected onto the front side of the target object and only lateral sides thereof can be illuminated.
Therefore, with regard to a short-range light source device used to provide light supplement in assisting image capture for short distance photography, issues concerning illumination of longer duration in time on the required image capture area, correct light supplement direction for casting light on the front side of the image capture area, along with precise light supplement adjustment for illumination angle or even anticipated shadow effect caused by light source of light supplement so as to successfully obtain information of high precision on the target object, indeed have to be addressed.